I am doing exploratory research on the nature of color perception. In order to develop operational definitions, could I ask you to help me out by ordering the following colored squares? Please send a private message (below) with your response/order. I know this is not an easy task, thank you so much for helping me out here!

Please order the colours.

The idea that the brain of the neonate begins as a “tabula rasa”, and that the complex precepts of the adult can be traced back to a history of learned associations made from the time of brith, originated in empiricism, sets the foundational ground to modern neural network or connectionist theories, whereby individual sensations are related to the activation of individual neurons, or neuron assemblies in the brain expressed by Hebbian learning.

It is, however, hard to understand why we do not see the world as na assembly of dots

Seurat's painting The Circus

but as extended areas and volumetric bodies. Wolfgang Metzger (1936), identifies this problem, and develops a careful description and unbiased analysis of the phenomenological properties of visual perception. In his view, although there seems to be some sort of influence of experience on vision, the organization of the visual field occurs essentially without our involvement. It is, in fact, not to up to us to decide what and how we see. Rather, we already find the visual world ready-made before us: stimuli organize themselves in the simplest, most symmetrical, and balanced manner. Perceptual constancies (or invariances) is what warrantees that the same object in our environment changes little in perception even when physical conditions under which the stimuli occur vary: Perceptual constancies or invariances are the focus os experimental phenomenological analysis, which has fruitfully developed the Gestalt laws (see also the post on Gestalt and Qualitative Relations).

The world we see is not the world itself. Metzger, in his Laws of Seeing (1936), justifies such claims with three major observations:

There are percepts for which there is no direct correlate in the physical stimulus. Examples are brightness enhancement and illusory contours

Certain things are not seen though they are clearly before our eyes. Examples of this are objects that by their proximity and structure become part of an edge or become embedded in larger configurations (hidden objects).

We see objects, but differently from the way they are. Some examples are made from stimulus conditions (microgenesis) as well as many geometric-optical illusions, where we misperceive shapes, sizes, and angles of stimuli. These observations are undeniable, they cannot be overridden by better knowledge of the actual stimulus, and they have reality of their own.

Qualitative perception of Gestalt has more recently gained an increased interest in the area of cognitive science, particularly by virtue of its non-reductive metaphysics against strong neurocentred and artificial intelligence models. This work on the structures of cognitive and perceptual experience is today being rediscovered and potentially provides immediate relevance to physiologically oriented cognitive science. The theory of Gestalt is, of course associated with the members of Berlin School such as Max Wetheimer, Wolfgang Köhler, and Kurt Koffka, and with the members of the Austrian school, Graz School, such as Benussi and Kanizsa, but its roots date back to the remarkable work of Brentano and his students, Christian von Ehrenfels, Edmund Husserl and Carl Stumpf, whose work we shall investigate here, particularly in what concerns the genesis of the concepts of complex and Gestalt.

1. Ehrenfels “On Gestalt Qualities”

The seminal paper by Ehrenfels “On Gestalt Qualities” (1890), is concerned with the reflections on the question “what complex perceived formations such as spatial figures or melodies might be”. The answer to this question requires the doctrine of intentionality by Brentano and the works on the ontology of the mind by Husserl. As it is well known, for Brentano, there are both simple and complex mental acts between the intuitive and the non-intuitive components of psychic phenomena of different sorts, between the various different sorts of phenomenally give boundaries and continuity.

The essay on “Gestalt qualities” consists in a conceptual proposal. Ehrenfels suggests that the German term ‘Gestalt’ which means ‘shape’, ‘figure’, ‘form’ should be generalized in a certain way. In his and Brentano’s view a spatial shape or Gestalt is perceived ⎯ is given a in visual presentation ⎯ on the basis of a complex of sensations of individual elements having ‘distinct spatial determinations’. In seeing the elements and their spatial determinations, one is able to apprehend the shape as an additional object (quality, attribute) as it were side by side with its associated elements. Our total experience is, therefore, something distinct from the experience of a mere sum or complex of sensory elements. What Ehrenfels proposes is that wherever we have a relation of this sort, between a complex of experienced elements on the one hand and some associated unitary experience of a single invariant structure on the other. This ‘structure’ should be conceived as the Gestalt. The unitary experience is structurally analogous to the experience of a spatial shape.

The Gestalt concept is then generalized further to embrace also complex objects of experience founded on inner perceptions ⎯ one’s presentations of one’s own elementary feelings, acts, or mental states. Sensory data from different sensory modalities may, according to Erenfels, combine together in such a way to provide the foundation for mixed Gestalt qualities of specific sorts. Having identified spatial shapes, melodies, chords, and complex taste as first order Gestalt qualities founded on given elementary sensations, Ehrenfels recognizes that these qualities, too, may combine together in such a way as to found new, second orer qualities which are themselves capable of founding third order qualities, and so on, in principle without limit (Smith, 1988).

As it is now explicit, Gestalt qualities, for Ehrenfels, are not wholes embracing their fundamenta ⎯ tones, colours, tastes, smells ⎯ as parts. Rather, they are additional unitary objects, existing alongside the unitary elements with which they are associated. The Gestalt quality is not a combination of elements but ‘something new in relation to these, which exists together with [their] combination, but is distinguishable from it’. It is a special sort of structure, a ‘positive content of presentation bound up in consciousness with the existence of complexes of mutually separable elementary presentations’. For Ehrenfels there are also unitary entities at successively higher levels, what one might call relative elements or ‘quasi-substances’, objects which, even though they do not belong to the ultimate wordly furniture, are yet given to consciousness in an unitary way and have to be recognized as such by any adequate theory. The quality in question here is associated with, but not reducible to, complexes of points, lines, symptoms and events, apprehended direct and immediately.

Ehrenfels asks about the specific contents of the presentation, Is content a real entity? Something individual and spatio-temporal? Or is it rather an ideal or abstract universal, multiply exemplified in the acts of different subjets towards the same foundational elements? What is the structure of the “complex of presentations” that serves as the foundation or carrier of Gestalt quality?

Are we to acknowledge both Gestalt qualities and sui generis complexes, which they would be qualities of? And how is a complex of mutually separable elementary presentations related to those complex fusions of elements, which Ehrenfels also recognizes?

For Ehrenfels, so also for Husserl, we grasp the configuration and its quality in one glance ⎯ not by collecting together in intuition a sum or a sequence of objects or relations, as occurs in those higher order articulated acts of counting and calculating which are the main subject-matter of Husserl’s early work. Husserl explains this through the notion of ‘fusion’, a notion he takes from Stumpf, signifying the absence of phenomenal discontinuities or boundary lines, as for example when one perceives an array of colour in which there is a gradual transition from red to blue or a glissando in which one musical tone passes continuously into another ⎯ the relations between these relevant parts become thereby fused together (in a figural moment, in Husserlian’s terminology). Husserl ontology plays an important role to reflections raised in Ehrenfels paper. The Gestalt problem is, in effect, a problem of unity, and Husserl suggest there are two ways in which the unity can come: either objects are such that they don’t need additional objects to glue them together into a whole; or they are such that they are in themselves not sufficient to make a unity and require the presence of some additional object to glue them together. Such additional objects may be of two sorts: independent objects (like a mass of glue), or dependant objects, capable of existing only in consort with the objects they serve to unify (moments of unity or figural moments).​The moments of unity in Husserl’s phenomenology are important because they serve to bridge the ‘phenomenological’ and the ‘objective’ spheres. The subject and the object do not simply co-exist but are in fact related together in a single unified whole.

Carl Stumpf: phenomena of ‘fusion’

Ehrenfels’s dichotomy between complex of experienced elements on the one hand and some associated unitary experience of a single invariant structure on the other, can be further understood through Carl Stumpf’s central ideia of ‘fusion’ implies a anti-reductionist, descriptive attitude that represents an attempt to produce what we might call a natural philosophy of complex experiences, including not only the phenomena of fusion and purely aggregative phenomena, but also a range of different sorts of Gestalt phenomena considered to be lying between these two extremes.

Stumpf draws the very important distinction between complex and Gestalt. Complex is a whole of sense contents; and the latter, the relational attribute, the network of relations between those contents. This network is somehow unitary because when we hear a chord or a melody we hear a relational attribute, not a complex or succession of dyadic relations. The network has a structural dimension because it can be transposed, transferred from one complex of relata to another.

For this psychological mechanism to happen, Stump remarks, there must be something cognitive in our awareness. For to grasp a Gestalt is to grasp not merely an individual as such, but also the abstract net of transferable relations which is its essence (Stumpf, 1939/40, p. 229, 242). Thus, Gestalt can never be perceived of themselves but always only in and of some given formed material ⎯ a tone or phoneme or timbre are founding elements that may involve physical or physiological complexity, but it is phenomenologically non-articulated and therefore has no Gestalt. Because Gestalt phenomena are primarily given, we often see Gestalten without recognizing parts, in fact, it sometimes takes effort to delineate figures with their ground, to discriminate constituent parts (p. 247). A Gestalt is a whole of relations, but under certain circumstances only part of this whole may be perceived ⎯ and this part may be a Gestalt in its own right.

One can apprehend the Gestalt of a melody only when one has heard the entire sequence of tones in such a way that a total impression has been gained through a discursive process (see also the post Gestalt and Qualitative Relations)

But the effect of the melody on our feelings does not begin only after it has been completed: we follow it through in its development from the very beginning, accompany this development with expectations, surprises, tensions, releases, for which foundation is provided by repetition, similarities, and so on.

The special issue Quantitative Approaches in Gestalt Perception recently appeared on Vision Research constitutes a commendable tentative to show the state-of-the-art in today’s Gestalt perception, and its relation to potential quantitative measurements and precise mathematical models.

All the papers show the attempt approach Gestalt perception from a quantitative viewpoint in a series of psychophysical and neurophysiological researches. Hawkins et al. (2016), for instance, quantify how different the processing time of Gestalt is compared to a parallel race model, where the parts are processes in isolation, using reaction times on information-processing models. Accordingly, Jäkel et al., argue that characterizing the temporal dynamics of Gestalt phenomena seems like a good way to get a more direct quantitative handle on the underlying perceptual and neural processes. Which are what Spehar and Halim (2016) have done using psychophysics and Sanguinetti, Trujillo, Schnyer, Allen, and Peterson (2016) have also done it using EEG. Overvliet and Sayim (2016), measure the influence of different contexts on haptic discrimination. They study the role of contextual modulation in the quantification of perceptual target-flanker grouping in the performance of haptic domain, that is, in haptic vernier offset discrimination. Kimchi, Yeshurun, Spehar, and Pirkner (2016) study the quantitative effects of different contexts on attentional capture.In the same line, Hawkind, Houpt, Eidels, and Towsend (2016), made use of Systems Factorial Technology (SFT) “as a quantitative approach for formalizing and rigorously testing predictions made by local and Gestalt theories of features (p. 1, my emphasis) to test local feature of location and the emergent features of Orientation and Proximity in a pair of dots. The procedure involved measuring the response times from stimulus onset. Subjects were asked to press one button (‘no change’) if the probe dots were in the same locations as the reference squares and another button (‘change’) if the probe dots were in a different location. They finally, concluded their results, in conjunction with their modelling tools, favour the Gestalt account of emergent features. Lezama, Randall, Morel, and von Gioi (2016) also proposed an approach for the grouping of dot patterns by the good continuation law. A “quantitative measure of non-accidentalness is proposed, showing good correlation with the visibility of a curve of dots … [a] robust, unsupervised and scale invariant algorithm for the detection of good continuation of dots is derived” (p. 1, my emphasis).

Blusseau, Maiche, Morel, and von Gioi (2016), consonantly, measured the visual salience of alignments by their non-accidentalness. In their view “quantitative approaches are part of the understanding of colour integration and the Gestalt law of good continuation” (p. 1, our emphasis). They, thus present a new quantitative approach based on the ideal observer algorithm, which, in their view is able to detect non-accidental alignments. On the same line, Hock and Schöner (2016) study the grouping affinity of different surfaces in different contexts quantitatively. They suggest a non-linear dynamical system and they sketch a model to account for them.

Im, Zhong, and Halberda (2016) address the challenges of how to model human perceptual grouping in random dot arrays and how perceptual grouping affects human number estimation in these arrays. They introduce a modelling approach relying on a modified k-means clustering algorithm to formally describe human observers’ grouping behavior. Machilsen, Wagemans, and Demeyer (2016), also quantify density cues in grouping displays. They test a number of local density metrics both through their perfeormance as constrained observer models, and through a comparison with a large dataset of human detection trials.

Kimchi, Yeshurun, Spehar and Pirkner (2016), attempting to study the relation between perceptual organization and visual attention, ask the subjects to “indicate, as fast and accurately as possible, whether the upper line of the target was displaced to the right or left” (p. 36, our emphasis) (study 1); “the color of the changed element” (p. 40) (study 2); whether the upper line of the target was displaced to left or the right of the lower line by pressing one of two keys on the keybord” (study 1 and 3) (p. 36, our emphasis). Response times measurements allowed the authors to demonstrate that “when some of the elements in the display are organized by Gestalt factors into a coherent unit ¾ an object ¾ the presence of the object affects performance. Specifically responses were significantly faster when a target was irrelevant to the task at hand not predictive of the target, and was not associated with any unique transient” (p. 47, my emphasis).

Ouhnana and Kingdom (2016), using a novel method of reverse correlation, aimed to determine the properties of the binding of motion and position. “Observers were instructed to report the motion direction of the frontal plane of the target figure via a key press throughout the trial” (p. 61, our emphasis). Their claim their result suggest “that change-synchrony not common-fate underpins perceptual binding between context and target” (p. 67).

Hazenberg and van Lier (2016) on the other end, measured event-related potentials (ERPs) to study the influence of well-known objects of which the middle part was occluded. They conclude from their study that the interpretation of partly occluded shapes is not solely driven by stimulus structure, but it can also be influenced by knowledge of objects.

Erlikhman and Kellman (2016) studied how minimal formation of spatiotemporal boundary formation ¾ such as contours, shape, and global motion ¾ can produce whole forms and the nature of the computational processes involved.

Kwon, Agrawal, Li and Pizlo (2016) developed a model that aims to find the closed contour represented in the image, according to them, their “approach is practical because finding a globally-optimal solution to a shortest path problem is computationally easy. Our model was tested in four psychophysical experiments” (p. 1).

Keemink and van Rossum (2016) introduce a population model of primary visual cortex, expecting to contribute to a “unified and principled account of the good continuation law on the neural level” (p. 1).

Schmidt and Vancleef (2016) focused their study in contour integration and conceptual similarities between ladders and textures, asking whether ladders and texture processing require feedback from higher visual area while snakes are processes in a fast feedforward sweep. They tested this in a response priming paradigm, where participants responded as quickly and accurately as possible to the orientation of a diagonal contour in a Gabor array (target). They conclude that snakes, ladders, and textures do not share processing characteristics.

On a more processing predictive level, Wilder, Feldman, and Singh (2016) develop a probabilistic model of whole of whole shapes that gives rise to several distinct though interrelated measures of shape complexity. Gershman, Tenenbaum, and Jäkel (2016), likewise, describe a Bayesian theory of vector analysis and show that it can account for classic results from dot motion experiments, as well as new experimental data. Clarke, Ögmen, and Herzog (2016), on their end, offer a computational model for reference-frame with applications to motion perception.

Matin, and Li (2016) propose a multiscale dipole model, which quantifies the effect of the array of points on visually perceived eye level in terms of dipoles of various lengths that activate orientation and size specific neurons in visual cortex.

Dimiccoli (2016) presents a computational model that computes and integrates in a nonlocal fashion several configural cues for automatic figure–ground segregation. Their hypothesis is that the figural status of each pixel is a nonlocal function of several geometric shape properties and it can be estimated without explicitly relying on object boundaries. The methodology is grounded on two elements: multi-directional linear voting and nonlinear diffusion. Their results suggest that figure–ground segregation involves feedback from cells with larger receptive fields in higher visual cortical areas.

Schmidt, Spröte, and Fleming (2016) employed a dot-matching task to study in geometrical detail the effects of rigid transformations on representations of shape and space. They presented an untransformed ‘base shape’ on the left side of the screen and its transformed counterpart on the right (rotated, scaled, or both). On each trial, a dot was superimposed at a given location on the contour (Experiment 1) or within and around the shape (Experiment 2). The participant’s task was to place a dot at the corresponding location on the right side of the screen. By analysing correspondence between responses and physical transformations, they examined for object constancy, causal history, and transformation of space. They found that shape representations are remarkably robust against rotation and scaling.

The generality of the experiments in the special issue offer a quantitative model to the understanding of Gestalt phenomena, using one or another psychophysical method. The procedure ranges from button-pushes, response-times, neural correlates, to computational probabilistic processing. Awkwardly, not a single experiment addresses qualitative Gestalt relations, well evidenced by Ehrenfels, Stumpf, Mach, Meinong, and other Gestaltists. Nor the complexity of presentations, necessary for the existence of a given Gestalt quality. Rather, a simplistic approach to gestalt perception appears to be the preferred methodological strategy. It has to be acknowledged that nor times-response, nor button-pushes allow “the process of formation of the intuitive presentation directly from the indirect presentation . . . a process of change, which serves as the foundation for a specific temporal Gestalt quality” (Ehrenfels, 1890, tr. Smith, 1988, p. 104).

Reading the papers, however, one gets the impression of a gap between the theoretical commitment of the Authors (Gestalt perception) and the choice of quantitative methods to be applied to classical stimuli of psychophysics (metric quantities). One reminds of what Metzger (1971), Michotte (1991), Kanizsa (1979; 1991) (among the others) considered to be a Gestalt approach to perception, i.e. having for objects Gestalt qualitative phenomena without leaving the phenomenological domain; without, that is, referring to the underlying psychophysical or neurophysiological processes. In the original Gestalt theory the phenomena to be observed are not “representations of external stimuli”; rather they are internal presentations of active perceptual constructs, co-dependent on, but qualitatively unattainable through a mere transformation of stimuli (Mausfeld, 2010). One may observe that contemporary “Gestalt approaches” means something different, but if so, it has to be stated explicitly, or, more correctly, to name these researches with a different name.

To wit, a few of the Authors in the special issue, Jäkel, Singh, Wichmann, and Herzog seem to be aware of the absence of meaningful parameters in the current quantitative approach to Gestalt. In fact, they hope that in the future there will be mechanistic models of the dynamics of perceptual organization with meaningful parameters that can be fit to behavioural and psychophysical data simultaneously (p. 5). Jäkel and colleagues also acknowledge that “[a]ll the papers [in the special issue] try to be quantitative about Gestalt perception, but the field is certainly still far way from a common theoretical framework” (2016, p. 5).

The main point impeding the field to share a common theoretical framework, as acknowledged, however, will not be reached by adding and further clarify details within the shared approach. It should be noticed, nonetheless, that meaningful parameters are the qualitative aspects of perception, which cannot, by principle, be assessed solely by third-person quantitative measurements and mechanistic models. Certainly Gestalt phenomena can be measured and statistically analysed, but at issue is the very concept of “stimulus” in a Gestalt analysis, and the proper methods to apply as required by the original Gestaltists. The current states of affairs, as presented in the special issue, show excellent researches in psychophysics and neurophysiology, that can be at least correlated to, but not explicative of Gestalt qualitative phenomena. In this respect, the papers evidence how ill equipped vision science seem to be in what concerns conceptual tools to address Gestalt qualities.

There is a methodological problem displayed in this special issue. It is true that, as Jäke et colleagues observe, “Gestalt psychology is often criticized as lacking quantitative measurements and precise mathematical models” (p. 1). The question is what kind of measurement and of models scientists has to adopt, in identify and treat observables of a qualitative nature, rather than reducing them under the psychophysical experimental lens.

To understand the complexity of human perception, both methods, the psychophysical (quantitative), and the phenomenological (qualitative) are relevant, with various scientific achievements to their own credit. Quantitative psychophysical methods (such as reaction times, forced choice response), focus on sensory reduced stimuli, while qualitative methods (such as subjective evaluations in first person account) focus on usually complex stimuli, those to be found in our environment. However, because quantitative and qualitative objects of study differ but are related enough, a complementarity between approaches is strongly encouraged. Particularly because, as Herzogm Thunnel and Ogmen (2016), in the special issue point out, despite the insights of 100 years of Gestalt psychology, vision scientists, often too quickly assume an implicit given for granted idea of isomorphism between the world, neural circuits, and perception, which fails to explain many visual (and other perceptual) phenomena as well. The point is relevant, also in light of the recent efforts made by vision scientists in particular, in order to address the Gestalt question from a wider viewpoint (Albertazzi 2013; Wagemans 2015).

The reader is left with the impression that the basic problems of a Gestalt approach to perception (the nature of qualitative phenomena and their units of measurement, the kind of the correlation among the levels of perceived reality, the methods and the kind of models to be construed to represent them correctly) are still to be answered. It is apparent that a conceptual and methodological clarification are needed, since from a 'classic' gestaltic viewpoint the gist of the issue appears to head in the wrong direction.

The seminal article of Gestalt Theory, by Christian von Ehrenfels (1890), Über Gestaltqualitäten, begins with a review of Mach’s Beiträge zur Analyse der Empfindungen (Analysis of Sensations, 1886). Mach asks, “what constitutes a melody?” The relationships of the sound to one another, he answers. Although it seems empirically odd, the melody, he says, is not constituted out of its sounds, for different sounds can construct the same melody. Providing relationships remain the same, the recognition of the structure is possible. For Mach, this process is at the basis of all perception. Mach uses the term Gestalt to indicate the characteristics of a whole that depend on the specific configuration of its parts. Gestalten, for Mach, appear thanks to an equality (Gleichheit) in the sensations, which can be noticed directly, not deduced or abstracted. This, along with the discussion in the school of Brentano, constituted the starting point for Ehrenfels. Moreover, Meinong, Ehrenfels’ teacher, has dedicated a work to theory of relations (Meinong, 1882), and he is also very influential by explicity pointing out that relations are themselves nothing but Gestalt qualities. At the same time, Husserl also had used the term Gestalt and Gestaltmoment to indicate higer-order quasi-qualities.​Despite these parallels (see Albertazzi, 2001), it was Ehrenfels who tematized the topic. By asking “is a melody (i) a mere sum of elements, or (ii) something novel in relation to this sum, something that certainly goes hand in hand with but is distinguishable from the elements.” Like Stumpf (1890), he concluded that it is much more than the sum of the parts. “the qualities are not in the least changed … but a new relation is introduced between them, which establishes a closer unity than that between members of a mere sum (Stumpf, 1890, p. 64). In line with this theoretical background, and rejecting a simplistic approach to perception, Ehrenfels explains Gestalt as follows,

By Gestalt quality we understand a positive content of presentation bound up in consciousness with the presence of complexes of mutually separable (i.e. independently presentable) elements. That complex of presentations which is necessary for the existence of a given Gestalt quality we call the foundation of that quality (Ehrenfels, 1890; Smith, 1988, p. 93).Ehrenfels foci Gestalt qualities in its relations (Ehrenfels, 1890; Smith, 1988, p. 101), in which the movement of going from an unintuitive to the corresponding intuitive presentation gives rise to a Gestalt quality,

by Ludwig Wittgenstein, in Philosophical Investigations

Thus anyone confronted with, say, a complicated description of a work of architecture will first of all form a merely indirect presentation of it, which will then be rounded out by gradual execution or fulfilment of the various merely intended components, to yield an intuitive total picture. But this process of formation of the intuitive presentation directly from the indirect presentation is something that happens, a process of change, which serves as the foundation for a specific temporal Gestalt quality (Ehrenfels 1890, tr. Smith 1988, p. 104).Given the Gestalt nature of relations, Gestalt qualities can be compared to one another and give rise to increasingly higher order Gestalt qualities. Ehrenfels adds to this the “intimate unity with which we combine presentational contents of physical and psychical occurences” (Ehrenfels 1890, tr. Smith 1988, p. 107).

by Louis Albert Necker

Psychic phenomena are essentially distinct from ‘physical phenomena’, which for Brentano are immanent and intentional objects of the presentations themselves. A physical phenomenon is, thus, composed by two nondetachable parts, i.e. phenomenal place, and quality (Brentano, 1874/1995, pp. 77-80). Interlocked perceptual appearances, like colour, shape, and space, are in fact the initial direct information presented to us in awareness. They are not the primary properties of what are commonly understood as physical entities, even though they are correlated with stimuli defined on the basis of physics (Albertazzi, 2015). Appearances, in visual awareness, are not simply representations of ‘external’ stimuli; rather, they are internal presentations of active perceptual constructs, co-dependent on, but qualitatively unattainable through a mere transformation of stimuli (see Mausfeld, 2010).

Thus, the goal that should be pursued in the study of Gestalt qualitative relations is, the discover and analysis of necessary functional connections among visual phenomena, identification of the conditions that help or hinder appearance or the degree of their evidence, in other words: determination of the laws which the phenomenological field obeys. And this without leaving the phenomenological domain; without, that is, referring to the underlying neurophysical processes . . . The influence of such processes and activities certainly cannot be denied, but they must not be identified with seeing…The experimental phenomenology of vision is not concerned with the brain, but with that result of the brain’s activity that is seeing (Kanizsa, 1991, pp. 43-44).The study of Gestalt qualitative relations does not obviously deny the existence of stimuli, nor the correlation between the physical stimulus and the behavioural response, but stimuli are seen as the triggers to the perceptual experience. For that reason, the phenomenological method distinguishes between what concerns psychophysics of brain analysis, and what concerns qualitative analysis of the phenomena.